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ALEXANDER  VON  HTBCBOLDT.                191
new field of Ms pre-eminent activity., namely, tliat of
comparative climatology.
Hiimboldt lias a much more comprehensive view of
climate than has hitherto been accepted;  all terres-
trial forces are combined in it in his acceptation of the
term, and his explanation of the varying climates and
their causes is based on general scientific laws.    The
places he  connects by the isothermic lines  are far
from parallel with the equator, for the many causes
which modify the temperature influence their direc-
tion.    The temperature is raised in the  temperate
zone by vicinity to the western coast, to bays or lakes,
by the situation of the place in relation to large plains,
or oceans free from ice., by the prevalence of south or
west winds, by protecting  mountain-ridges,  by the
absence of marshes which would remain covered with
ice, by absence of forests on a sandy soil., by pure sky,,
and  by the vicinity of a warm ocean current.    The
opposite  of all these   must   make the   temperature
cooler, but in general in the temperate zones, especially
in Europe,  the   eastern   coasts  are   colder than the
western, because the east winds come over cold coun-
tries, the west winds come across the sea.    Humboldt
says, that the  studies  of his friend George Forster
have especially led him to these results.
As the temperature, properly, grows colder with the
height of latitude, or the distance from, the equator,
Humboldt paid especial attrition to this on his in-
vestigation of meteorological precedents, his institution
of botanical geography, and other scientific plans, and
he says that on his many journeys in and out of the
tropics the comprehension of this law of the decrease
of temperature with increasing latitude, has always
been a prominent subject for investigation. To these
may be added his results on the snow boundary, the
humidity and the thawing power of the air, and on
electricity.
But from this view of our planet, which he seems.
to have built before our eyes, Humboldt goes on to
the organic life of plants and animals  the animated